jackbootEnglishOxford New American Dictionaryjackboot /ˈjakˌbo͞ot, ˈdʒækˌbut / ▸ noun a large leather military boot reaching to the knee. ▪ [in singular] used as a symbol of cruel or authoritarian behavior or rule: a country under the jackboot of colonialism. – DERIVATIVES jackbooted /ˈjakˌbo͞odəd, ˈdʒækˌbudəd / adjective